Hitchcocks Forum

Just read johnos' post re fitting a one tooth bigger gearbox sprocket.This is something I have been toying with, but not sure if the rear chain will still be long enough. Also,how involved is it taking out the clutch, which I am reluctant to touch as it works really well.Since fitting electronic ignition the bike certainly feels like she could pull a higher gear, which in theory should give better economy. I'm not really concerned about higher top speed,though I guess it would be handy for A roads. In short is it a worthwhile mod ? The bike is a pretty standard iron barrel 500.

Wilf, going up one tooth from standard will be fine on the standard chain, i needed a longer chain for a 19 tooth which is 2 teeth up from standard..

One tooth gives an increase of approx 3mph at equivalent rpm which is not a lot but can be enough to dampen out some of the buzz when cruising at say 55-60mph

Its good that your not looking for overall speed increase and performance boost because you will find normally seated on a slight incline, the bike will run out of puff without some upgrading of horse power to cope.. Overall 18 teeth is a good compromise for A+B road work...

I changed the sprocket on my 2012 B5 efi so wouldn't like to comment on the effect of fitting one on an iron barrel, there are plenty of owners who may have done this to the older bikes.
I know most bikes will pull a 1 tooth larger sprocket than standard as manufacturers will always compromise on speed and power to find a middle ground suitable for everyone.

On my B5 it seems a 1 tooth sprocket has changed engine rpm by 5mph, removing most of the drive train led vibration, it is a lot more comfortable to ride which suits me as I often do trips of 100 miles or more and don't need a vibration white finger to spoil my day!
I did fit a 1 link longer chain (102) instead of the 101 chain that was originally fitted, but looking at it, a 101 chain would still have worked as the snail cam adjusters are 1/2 way round the cam from fully forward so I may yet remove a link if initial chain stretch requires it.

Top speed is around the same as original as the B5 runs out of puff at the top end (around 85mph for the B5), although the wind resistance from the fairing and leg-shields will not help here, however cruising at my normal fast A road/motorway speed of 65mph is much better and it feels like the Bullet will maintain this speed all day without vibration or engine stress.

One downside is that in town (30mph) I now have use a lower gear which equates to more fuel in the long run, but, I think that will change when I can afford to do the next step and fit an EFI short exhaust and a K&N air filter then in a year or so maybe a power commander as I have read good reports from those that have done this modification in the Americas.

Excuse my ramblings
give it a go if that's what you want to do, the good thing is if fitting a larger sprocket is not suited to your riding style then it is a mornings job to put the original chain and sprocket back on reverting back to standard
johno

Worth doing if the exhaust is free flowing and carb. jetted up Wilf

Out of interest can you get O ring chains for 5 speed iron barrels!

Grumps it is a 530 chain get it in whatever you want, I make a spacer to go between the inner primary and the crankcase and the chain clears no problems. Spacer is about 2mm thick and it gives enough clearance

Sounds like it's worth dong alright. My only reservation would be in having a o remove and replace the clutch, which is a treat to use. Don't want to screw things up. I'm assuming the clutch has to come out to get at the sprocket.
Thanks for the comments.

Whoo----!Just priced up all the special tools needed to change the sprocket. I'm not saying it's not worth it, but at the end of the day I don't think I want to spend £100 or so. Tinkers running good enough as she is.
Once again thanks for all the advice lads.

Special tools?

Scuse my igrance, according to our hosts technical notes I'll need a clutch holding tool, a puller and a couple of other yokes. Each at £20ish by the time vat and delivery are added. Or--can the job be done as well without? I did manage to use a 12" piece of pipe and a spring luggage scale as a torque wrench when changing Tinkers head gasket.